Fly fishing enthusiasts know that the best time of day for fishing is at dawn or dusk. However, in the dim light conditions during these hours it is difficult to thread the fishing line (leader or tippet) material through the eyelets of small hooks to secure the fly. This is especially true for persons whose eyesight is impaired due to disease or injury.
The threading process is also hindered when excess head cement or fly tying materials obstruct the eyelet of the hook.
This same device may be used by sewing enthusiasts to thread needles where additional light is needed on the eyelet of the needle.